Comparable outcomes after total knee arthroplasty in patients under 55 years than in older patients: a matched prospective study with minimum follow-up of 10 years.

PURPOSE: To compare outcomes after TKA for osteoarthritis between patients younger than 55 years and older patients. METHODS: A cohort of 61 patients aged 55 years or younger was prospectively matched for gender, body mass index and knee function with patients with median age of 66 (range 60-70) years. Clinical evaluation was performed by the Knee Society scores (KSS), reduced Western Ontario and McMasters Universities (WOMAC) and Short-Form 12 (SF12) questionnaires. Radiological evaluation was also performed. RESULTS: The median follow-up was 12 (range 10-14) years. Survival at 14 years was 96.7% (95% CI 92-100%) in the younger group and 98.2% (95% CI 95-100%) in the older group (n.s.). There was no deep infection or loosening of femoral or patellar component in either group. In the younger group, 2 patients required revision (aseptic tibial loosening at 8 years, and polyethylene wear at 10 years). In the older group, there was 1 revision (aseptic tibial loosening). Revision rate was not significantly different (n.s.). Multivariate analysis showed no significant relationship between revision and age, gender or BMI. At 5-year follow-up, there were no significant differences between groups in KSS knee or function, WOMAC pain or function, or SF12 physical or mental, but in the last evaluation there were better results in younger patients for KSS-function (p = 0.018), WOMAC-function (p = 0.028), SF12-physical (p = 0.001) and SF12-mental (p = 0.035), although these differences were not clinically relevant. A significant decline was noted for KSS-function in either group from 5-year to at last follow-up. CONCLUSIONS: The TKA survival in younger patients was comparable to older active patients, without increased complications or revisions at a minimum follow-up of 10 years. Primary hybrid TKA can provide successful pain relief, function and quality of life in younger patients than 55 years with osteoarthritis. TKA is a suitable option for these young patients with appropriate surgical indications. LEVEL OF EVIDENCE: II.